Boston Marathon bombings: Whatever happened to terrorism alerts?

The federal government's response to the Boston Marathon bombings has not included public terrorism alerts, a major change from past attacks.After the 2001 attacks on the World Trade Center and the Pentagon, the Department of Homeland Security created a color-coded system to warn the public about potential terrorism threats.That system was replaced in 2011 by a more specific text-based alert system. But the agency has not issued an alert under the new system in the last two years.In part, that …